1. Field of the Invention
This invention relates to a process for producing a tissue-equivalent membrane for use on burns, cuts or other wounds to protect an affected part and provide an optimum condition for the proliferation of epidermal cells, and, more particularly, to a tissue-equivalent membrane prepared by extraction from an esophagus of bovine origin.
2. Description of the Prior Art
Wounds which involve injuries to significant areas of human skin are difficult to treat. Covering the wound is an important aspect to successful care, and is often limited by lack of suitable autograft material. Because of this limitation, several temporary coverings have been developed and used. However, none of these has achieved the total benefit which results from an autograft. Products used as temporary coverings include human allografts, xenografts (e.g., pigskin), and a variety of manufactured membranes. Examples of patents of this type include:
U.S. Pat. No. 4,299,819 issued on Nov. 10, 1981 to Magdelena G. Eisenger discloses a process for treating burn victims wherein human epidermal cells are grown in a tissue culture medium having a pH from about 5.6 to 5.8. The edges of the sheet thus grown are separated from the tissue vessel and then applied to a transfer member (a collagen sponge or dermal side of porcine origin is discussed, along with using the pateint's own skin). This aggregate is then applied to the wound site. The novelty in the disclosure is that only epidermal cells are used, which retain the ability to differentiate into multilayered structures.
U.S. Pat. No. 4,446,124 issued on May 1, 1984 to Charles L. Fox, Jr. et al. discloses a wound dressing comprising silver sulfadiazine incorporated in animal tissue wherein, to minimize the possibility of bacteria that might have entered the wound before the dressing is applied, the dressing is prepared by placing it in an aqueous solution containing ammoniacal silver sulfadiazine for a period of time. Alternatively, one could spray the dressing with the solution. After the ammoniated silver sulfadiazine is incorporated into the tissue matrix, the dressing is partially dried and stored in sterile circumstances for later use.
U.S. Pat. No. 4,485,096 issued on Nov. 27, 1984 to Eugene Bell discloses a tissue equivalent and method of preparation wherein a hydrated collagen lattice is formed in vitro and is used as a substrate for different types of tissue equivalents. Skin equivalent is formed by plating keratinocyte cells on this substrate. Small vessel equivalents are formed by growing smooth muscle cells within the lattice and wrapping the aggregate about a glass rod or other mandrel and then plating fibroblast and endothelial cells on the outer and inner layer, respectively, of the product obtained. Gland/organ equivalents are formed by introducing glandular cells of the specific type required into the lattice. Bone equivalents can be formed by incorporating demineralized bone powder into the hydrated lattice contracted with fibroblast cells, the required shape being produced by the mold in which the aggregate is cast.
U.S. Pat. No. 5,015,584 issued on May 14, 1991 to Miriam M. Brysk discloses an epidermal graft system wherein epidermal cells are cultured in an appropriate medium and when sufficient for the purpose, they are enzymatically detached from the container and laid on a collagen coated dressing.
These patents, and other analogous known methods of skin autografting, allografting, and xenografting may represent progress in the field of wound coverage, but do not provide an optimal, or in some cases, a variable alternative as a medical treatment for many skin injuries. Much of the prior art is dependent on complex lab procedures involving equipment that might not be available in some parts of the world, or in certain crises or disasters. Moreover, none of these, either taken singly or in combination, disclose the novel tissue-equivalent membrane produced by the process disclosed herein form an esophagus of bovine origin.